Model-based assessment of muscle forces and strain distribution in the femur of Cabot’s Tragopans(Tragopan caboti)

The hindlimbs play a crucial role in bird locomotion,making the biomechanical properties of the musculoskeletal system in these limbs a focal point for researchers studying avian behaviour.However,a comprehensive analysis of the mechanical performance within the long bones of hindlimbs during locomotion remains lacking.In the present study,the strain and deformation of the femur of Cabot’s Tragopans(Tragopan caboti)were estimated.We employed inverse simulation to calculate the force and moment of femoral muscles during mid-stance terrestrial locomotion and conducted finite element analysis to calculate femoral strain.Results showed that during mid-stance,the femur experiences combined deformation primarily characterized by torsion,bending,and compression.It emphasises the importance of considering the influence of varying loads on bone adaptation when investigating bone form-function relationships.Muscles were found to play a significant role in offsetting joint loads on the femur,subsequently reducing the deformation and overall strain on the bone.This reduction enhances femoral safety during locomotion,allowing birds to meet mechanical demands while maintaining a lightweight bone structure.Notably,the M.iliotrochantericus caudalis significantly reduces torsional deformation of the proximal femur,protecting the vulnerable femoral neck from high fracture risk induced by rotation load.Given that the femur torsion during terrestrial locomotion in birds is associated with changes in hindlimb posture due to their adaptation to flight,the characteristics of M.iliotrochantericus caudalis may provide insight into the locomotor evolution of theropods and the origin of avian flight.

一流大学数字化转型实践与探索——浙江大学的经验和模式

在实施国家教育数字化战略行动中,高等教育尤其是一流大学如何进行数字化转型,是一个重要课题。为此,文章以浙江大学为例,在分析数字化带给一流大学发展机遇和挑战的基础上,介绍浙江大学数字化转型的主要做法及其成效。为大力推进数字化转型,浙江大学重点采取以下五项举措:立足“服务一流”,做好数字化转型顶层设计;部署“云网数端”一体化先进技术路线;践行“从小事做起”的小切口推进策略;探索“以事组班”的跨组织创新机制;坚守“师生为本”的人本化服务理念。通过这些举措,构建了集数字化教学、科研和校务服务于一体的“网上浙大”,并取得五大成效:提升校园空间智慧化能力,提高办学空间亩效比;建立混合式教学平台,推动教学范式创新;建立开放互联科研云环境,推动协同联动的学术创新;建立新型教育治理模式,提升现代校务治理水平;建立校园数管模式,提升校园智慧管理服务能力。以此为基础,文章对高校数字化转型的方向与路径进行思考,并提出确立价值赋能观念、推动组织转型创新、采用先进技术支撑、建立专业人才保障、联合生态共生共赢等建议。文章认为,浙江大学有效探索和实践了数字化环境下一流大学的组织创新,以数字思维和技术激活“教学相长”、科研创新和治理变革,可以为教育数字化转型特别是高校数字化转型提供典型经验和模式。

基于液体透镜自动聚焦显微成像系统设计

设计一种新型自动聚焦显微成像系统,该设计在不移动显微镜或像面情况下,利用液体透镜调节显微成像系统筒镜焦距,对物距离焦进行补偿。本文介绍了微流体透镜调焦方法,理论推导出物距与筒镜焦距的关系曲线。通过ZEMAX优化,设计出一套自动聚焦显微成像系统。该系统以数值孔径为0.25的10×无穷远平常消色差显微为物镜,以液体透镜和4片球面透镜为筒镜,空间分辨率达到1.22微米,物距可离焦范围为±0.5 mm。在不同物距离焦情况下,系统光学传递函数在72 lp/mm处均大于0.2。该设计具有结构紧凑、无机械运动部件、反应速度快等特点,大幅降低了光机系统复杂性。

Femoral mechanical performance of precocial and altricial birds:a simulation study

Background:As the major load-bearing structures,bones exhibit various properties related to mechanical perfor-mance to adapt to different locomotor intensities.The habits and ontogenetic changes of locomotion in animals can,thus,be explored by assessing skeletal mechanical performance.Methods:In this study,we investigated the growing femoral mechanical performance in an ontogenetic series of Cabot’s Tragopans(Tragopan caboti)and Pigeons(Columba livia domestica).Micro-computed tomography-based finite element analysis was conducted to evaluate the stress,strain,and strain energy density(SED)of femora under axial and radial loading.Results:Femora deflected medio-laterally and dorso-ventrally under axial and radial loading,respectively.Femora deformed and tensed more severely under radial loading than axial loading.In adult individuals,Cabot’s Tragopans had lower strain and SED than pigeons.During ontogeny,the strain and SED of pigeons decreased sharply,while Cabot’s Tragopans showed moderately change.The structural properties of hatchling pigeons are more robust than those of hatchling Cabot’s Tragopans.Conclusions:Limb postures have dominant effect on skeletal deformation.The erect posture is preferred by large mammals and birds to achieve a high safety factor of bones during locomotion.Adult Cabot’s Tragopans have stronger femora than pigeons,reflecting a better bone adaption to the terrestrial locomotion of the studied pheas-ant species.Changes in strain and SED during growth reflect the marked difference in locomotor ability between precocial and altricial hatchlings.The femora of hatchling Cabot’s Tragopans were built with better energy efficiency than deformation resistance,enabling optimized mechanical performance.In contrast,although weak in mechani-cal function at the time of hatching,pigeon femora were suggested to be established with a more mature structural design as a prerequisite for rapid growth.These results will be helpful for studies regarding developmental patterns of fossil avian species.

Muscle architecture of the forelimb of the Golden Pheasant(Chrysolophus pictus)(Aves: Phasianidae)and its implications for functional capacity in flight

Background: Flight is the central avian adaptation in evolution. Wing muscles form an important anatomical basis for avian flight, affecting wing performance and determine modes of flight. However, the roles of distal muscles in adjusting the wing, as well as their functional specializations, remain largely unknown. The importance of muscle fiber architecture has long been recognized. In this study, we provide quantitative anatomical data on the muscle architecture of the forelimb of the Golden Pheasant(Chrysolophus pictus), with an emphasis on brachial,antebrachial and manual segments.Methods: The forelimbs of five Golden Pheasants were dissected and detailed measurements of all muscles were made, including muscle mass, muscle belly length, fascicle length. From these values, muscle volume, physiological cross-sectional area(PCSA) and maximum isometric force were derived.Results: General trends such as the distribution of muscle mass, fascicle length and the ratio of tendon length/belly length are revealed. Comparing PCSAs between antebrachial depressors and elevators and between intrinsics of the alular digit and major digit yielded significant differences(p < 0.05). Pronounced development of the antebrachial depressors suggests that ventral rotation of the distal half of the wing is a pivotal factor in shape change and orientation modulation. Large PCSAs in tandem with the force generation capability of the major digit intrinsics may help stabilize the digits while enhancing support of the primary feathers. The architectural properties of the alular digit confirm that alular adjustment is essential to rapid adduction and abduction.Conclusions: These observations illustrate the underlying structural basis for the functional capacities of the distal forelimb muscles and may provide additional information useful in further biomechanical and in vivo investigations.

Myological variation in the hindlimb of three raptorial birds in relation to foraging behavior

Raptors share a common predatory lifestyle,but are different in food preferences and hunting behavior.The grip force and talons’grasping capabilities are fundamentally crucial for subduing and killing their prey to feed,but the abilities and differences to generate force are less known.In this study,the entire pelvic muscles were dissected with the muscle mass and fibre length measured and physiological cross-sectional area counted in the Common Kestrel(Falco tinnunculus),Eurasian Sparrowhawk(Accipiter nisus),and Long-eared Owl(Asio otus).Statistical tests were performed to explore the possible differences in architectural parameters among species.These species were same in distributing the greatest proportion of muscle mass to the shank region and the digital flexor functional group,allocating more than 60%muscle mass in relation to total single leg muscle mass to the same seven individual muscles including flexor digitorum longus(FDL),flexor hallucis longus(FHL),and tibialis cranialis(TC)which are three major muscles responsible for talon closure.Interspecies differentiations were most present in the shank and tarsus instead of other regions of the leg,which might reflect their difference in hunting mode and foot use.Greater force-generation capacity of FHL and some anatomical features suggest that digits 1and 2 work together as an efficiently vise-like set,playing more critical role than digits 3–4 in foraging of diurnal raptors but to a different degree.In accordance with zygodactyl foot morphology,each digit of the Long-eared Owl plays a subequal role when hunting,evidenced by anatomical and architectural features.Because of its unique insertion to the base of the pygostyle,the striking numerical difference in the development of M.caudofemoralis was possibly related to raptors’flight behavior and feeding ecology.Concluded from anatomical and architectural aspects,the similarities and differences of the hindlimb musculature were correlated to common predatory lifestyle and different foraging behaviors in three raptor species.These results illustrated the underlying myological basis for the functional capacities of the leg muscles and may provide additional information useful in further biomechanical investigation and computer simulation.

人工智能赋能高校韧性教学生态的路径研究

新冠疫情的反复使得师生频繁切换不同的混合式教学模式,这对教育韧性生态系统提出更高要求,依靠人工智能赋能韧性教学生态成为当前重要的研究课题。然而,现有研究缺少从系统性的视角综合分析韧性教学生态的构建路径。针对此问题,本研究以Z大学为案例,一方面探讨人工智能赋能韧性教学生态的框架和表现形态,另一方面对人工智能赋能下韧性教学生态的实践经验和教学效果进行分析。研究发现:Z大学以中台架构为技术底座丰富教学平台的功能应用,并贯穿导学、讲授、协作、评价四个阶段,有效地保障了疫情反复过程中师生对环境异化的适应性和教学效果的有效性。最后展望未来人工智能赋能韧性教学生态的发展重点,并对潜在的挑战进行反思。

细胞间线粒体成分转移触发缺血性心肌纤维化

心肌纤维化是引发心源性猝死的重要原因.心肌缺血/再灌注(MI/R)损伤可导致心肌细胞损伤甚至死亡,而成纤维细胞却出现激活并导致纤维化.目前,导致这一矛盾现象的细胞间通讯机制仍不清楚.小细胞外囊泡(small extracellular vesicles,sEVs)在细胞间通讯中起重要作用.但是,sEVs是否介导以及如何介导MI/R后心肌细胞和成纤维细胞间的通讯尚不清楚.本研究通过在体MI/R模型和细胞学实验发现,MI/R损伤情况下存在一种心肌细胞来源的sEV(Myo-sEV^(I/R)),其内容物富含线粒体成分.Myo-sEV^(I/R)被成纤维细胞摄取并触发纤维化.通过生物信息学筛选和实验验证,新发现Ambra1是Myo-sEV^(I/R)中的关键组分和潜在标志物.并且证实,Ambra1+-Myo-sEVs的释放是由MI/R损伤后心肌细胞的分泌型自噬所驱动,而不是经典的降解型自噬.在缺血和缺血周边区域,Ambra1^(+)-Myo-sEVs被成纤维细胞内吞导致跨细胞线粒体成分传递;线粒体DNA(mtDNA)激活cGAS-STING通路,促进成纤维细胞的活化和增殖.此外,数据显示,Ambral定位于Myo-sEV^(I/R)表面,心脏特异性的下调Ambral可抑制Ambral^(+)-Myo-sEVs的释放和成纤维细胞摄取,有效抑制缺血后心肌纤维化.本研究新证实了心肌分泌型自噬可介导缺血后心肌纤维化发生过程中的细胞间通讯.Ambral是Myo-sEVs的潜在标志物和特征分子,并具有重要的生物活性.本研究为缺血后心脏重塑提供了新的治疗靶点.

Numerical study of short-circuiting flow and particles in a gas cyclone

Short-circuiting flow is an important secondary flow in gas cyclones, which has a negative impact on the separation performance. To improve the understanding of the short-circuiting flow and guide the optimization of gas cyclones, this paper presents a numerical study of a cyclone using computational fluid dynamics. Based on the steady flow field, three methods were adopted to investigate the formation mechanism and characteristics of the short-circuiting flow and particles. The temporal variation of the tracer species concentration distribution reveals that the formation mechanism of the short-circuiting flow is the squeeze between the airflows entering the annular space of the gas cyclone at different times. The short-circuiting flow region, distinguished through the spatial distribution of the moments of age, is characterized by a small mean age and a large coefficient of variation. The proportion of the short-circuiting particles increases with the increase of the inlet velocity only for small particles. But with the increase of particle size, the proportion of the short-circuiting particles decreases faster at higher inlet velocities, resulting in significant differences in collection efficiency curves.

辣椒疫霉质外体疏水小蛋白SCR82编码基因的转录特征、异源表达和功能

[目的]分析PcF/SCR质外体疏水小蛋白SCR82编码基因在辣椒疫霉生长发育和侵染寄主阶段的转录特征,克隆其cDNA和基因组全长序列,分析蛋白性状及其序列保守性,利用大肠杆菌表达并获得纯化蛋白,分析其生物学功能。[方法]提取辣椒疫霉菌丝、游动孢子囊、游动孢子、萌发休止孢和7个侵染时间点(1.5、3、6、12、24、36、72 h)的本氏烟根部总RNA,利用半定量RT-PCR分析scr82的转录表达水平;通过高保真PCR从萌发休止孢cDNA和基因组DNA中克隆出该基因全长序列;利用软件对SCR82进行生物信息学分析,挖掘其他物种中的同源序列,预测蛋白性状;将cDNA全长序列克隆到含6×His-SUMO序列的pET28a(+)中,在不同温度(22、37℃)和IPTG浓度(0.1、0.2、0.5、1.0 mmol/L)组合条件下利用大肠杆菌Rossette 2菌株表达该蛋白,利用Ni2+亲和层析柱纯化蛋白;将蛋白浸润本氏烟和拟南芥叶片,分析它是否引起植物细胞死亡,蛋白浸润12、24 h后利用RT-qPCR分析本氏烟中3个抗性相关基因(NbMC1、NbSOD、NbPOX)的表达量变化。[结果] scr82基因在辣椒疫霉萌发休止孢和侵染寄主阶段上调表达;该基因为辣椒疫霉中单拷贝基因,不含内含子,开放阅读框为249 bp;预测其编码82个氨基酸,包含长度为21个氨基酸的信号肽序列和7个半胱氨酸但不含有任何已知功能域,蛋白疏水性强,二级结构主要为α-螺旋和不规则卷曲,在疫霉菌中保守;含重组质粒的菌株在22℃经0.2 mmol/L的IPTG诱导过夜(~16 h)产生大小约24 kDa的融合蛋白,纯化获得30 mg/mL的可溶性蛋白;融合蛋白不引起本氏烟和拟南芥叶片的细胞死亡,但导致本氏烟抗性相关基因均上调表达。[结论]本研究获得了辣椒疫霉胞外疏水小蛋白SCR82的原核表达蛋白,该蛋白不引起植物细胞死亡,但触发植物的防卫反应。

Experimental and numerical study of a gas cyclone with a central filter

This paper studies a novel gas cyclone with a cylindrical fiter face installed in the center from the vortex finder to the bottom hopper.The experimental results show that this composite cyclone has a higher collection fficiency and a lower pressure drop than the original cyclone.The mechanisms for the improvement are analyzed by both physical experiments and numerical simulations.By measuring dust samples collected at different places it is revealed that the center filter can prevent fine particles from entering the inner vortex and escaping,which accounts for the increase of the collection eficiency.In addition,the flow field of the composite cyclone is simulated by computational fluid dynamics and compared with that of the original cyclone.The analysis shows that with the filter layer installed,the swirling flow disappears in the vortex finder,which decreases the kinetic energy dissipation and hence lowers the pressure drop.

Multiple-quantum-well-induced unipolar carrier transport multiplication in AlGaN solar-blind ultraviolet photodiode

AlGaN solar-blind ultraviolet(SBUV)detectors have potential application in fire monitoring,corona discharge monitoring,or biological imaging.With the promotion of application requirements,there is an urgent demand for developing a high-performance vertical detector that can work at low bias or even zero bias.In this work,we have introduced a photoconductive gain mechanism into a vertical AlGaN SBUV detector and successfully realized it in a p-i-n photodiode via inserting a multiple-quantum-well(MQW)into the depletion region.The MQW plays the role of trapping holes and increasing carrier lifetime due to its strong hole confinement effect and quantum confinement Stark effect.Hence,the electrons can go through the detector multiple times,inducing unipolar carrier transport multiplication.Experimentally,an AlGaN SBUV detector with a zero-bias peak responsivity of about 0.425 A/W at 233 nm is achieved,corresponding to an external quantum efficiency of 226%,indicating the existence of internal current gain.When compared with the device without MQW structure,the gain is estimated to be about 103 in magnitude.The investigation provides an alternative and effective approach to obtain high current gain in vertical AlGaN SBUV detectors at zero bias.

Anti-Inflammatory Glycosaminoglycan Oligosaccharides from Colwellia psychrerythraea 34H Capsule:Synthesis and Biological Evaluation

Capsular polysaccharides(CPS)of Colwellia psychrerythraea 34H consist of linear tetrasaccharides repeating units in a glycosaminoglycan-like fashion.Their biological function is likely involved in the cold adaptation of microbial organisms.The low availability of these glycosaminoglycan structures greatly limits the study of their functions and biological activities.Here,an efficient semisynthetic strategy for CPS tetrasaccharide derivatives is achieved by using disaccharide units degraded from hyaluronic acids.This new synthetic process is suitable for largescale preparation,and several rare tetrasaccharide derivatives containing GalA-GalNAc were readily obtained in high yields.Biological evaluation of their anti-inflammatory effects demonstrated that these CPS tetrasaccharides effectively attenuated the lipopolysaccharide-induced sepsis and acute lung injury by decreasing macrophage infiltration and secretion of microphage-related cytokines in mice.All these results suggest that this new type of CPS tetrasaccharide can be developed as an anti-inflammation agent.